This invention relates generally to the distribution of television programming from an originating facility to one or more remote locations, and, more particularly, to a control system for automatically and remotely controlling head-end equipment at each of one or more local cable television systems.
The use of satellites for the distribution of television signals has made possible the delivery of a wide variety of news, entertainment, educational and sports programming to cable system subscribers. Examples of one type of provider of subscription programming are Home Box Office (HBO) and Showtime, the offerings of which a cable subscriber can purchase on a month-to-month basis. For delivery of such programming it is necessary to uniquely identify each channel (e.g., HBO) so as to be able to instruct the converter box in the subscriber's home which channel or channels it is authorized to descramble and which are not authorized. This is rather easily achieved by the cable operator assigning a unique tag to each of the channels it is offering and transmitting the tag data, along with other data, to the subscriber's converter box to precondition the box to descramble the ordered program signal when it arrives, usually at a specified time of the day established by the program originator.
Following the launch in November, 1985 of regularly-scheduled satellite Pay-Per-View (PPV) service, whereby a cable subscriber instead of subscribing to a particular entertainment channel on a monthly basis can with a telephone call order a single program event, such as a movie, and be charged only for what was ordered, cable systems operators discovered that their in-place hardware presented obstacles to full participation in this potentially profitable service. Specifically, the addressable hardware at the head-end of the cable system did not allow the showing of multiple events in a 24-hour period because most billing systems then in use depended on tag or address data for program identification in order properly to bill the customer. As noted above, tag levels were initially designed to work with monthly pay services.
Since a program originator or provider may offer ten showings a day of as many as four different movies, it is essential that any cable operator offering PPV be able to bill each of its subscribers for each and every showing of a movie or event ordered and watched by the subscriber. At first blush it would appear that this could be accomplished simply by changing the tag before each event, but the implementation turned out to be more difficult than would at first appear. Some cable system operators positioned an employee in the head-end facility to manually change their tags for each event. Not only was it costly to keep employees at the facility, day and night, to manually switch the tag levels, it severely limited the number of PPV movies that could be distributed per day, which, of course, limited the income of both the program originator and cable system operators.
A solution for those cable operators wishing to redistribute PPV programming distributed by a program originator, described in an article entitled "Satellite Delivered Tag Change System", by Andrew Ferraro, the applicant herein, published in 1987 NCTA Technical Papers, provided a control system for accomplishing the necessary switching at the cable operator's facility which was completely transparent to the cable operation. Message information in the form of a serial data stream encoded in accordance with the requirements of each of a multiplicity of local cable system operators is automatically generated under computer control at the originating facility and delivered by satellite to a network of cable system operators. Prior to the start of a particular Pay-Per-View event or program, the encoder equipment transmits a first message which preconditions addressable equipment at the cable system head-end to cause it to respond to a particular tag level upon later receipt of an authorization signal. The unique tag assigned to a particular program or event by an individual cable operator is stored in the originator's encoding equipment and, prior to the start of transmission of that particular scheduled program, the encoding equipment individually addresses the head-end equipment at each local cable site and downloads each cable operator's unique tag for that particular program. That is to say, the head-end equipment of all of the local cable systems is conditioned to receive the next tag value, but a tag change is not actually initiated until a subsequent message signal authorizing the change is received. The authorization signal is transmitted to the head-end of all of the cable sites simultaneously with the initiation of the program or event, thereby instructing each previously preconditioned cable head-end to insert the previously downloaded and stored tag into the composite video signal that is transmitted over its cable system. During the period between receipt of the preconditioning signal and the scheduled start time for the particular program, the head-end equipment of each system automatically distributes the tag to its individual subscribers who have ordered the program to establish descrambling authorization for those subscribers.
In this earlier system, a Commodore 64 computer installed in each cable head-end accepted the serial data stream message information and converted it to a parallel output for effecting switching operations. It was inexpensive and reliable, had the required non-volatile memory and its game cartridge port enabled a programmable ROM to be programmed with all the needed information and look-up charts.
Although this system allowed a cable operator to enter the PPV business from an operational point of view without extensive hardware upgrades and without additional manpower, because the timing of the preconditioning and authorization messages was geared to the beginning of a movie or other program event, the uneven lengths of movies frequently resulted in breaks between successive movies. This otherwise wasted break time could advantageously be used by individual cable operators to transmit short messages to its subscribers, including "teasers" such as a short segment of the movie to follow and instructions as to how the subscriber can order the program. Further, this earlier system cannot accommodate timely switching into the program distribution network of important news events, for example, carried by a satellite transponder different from the one used by the program originator.
It is, therefore, a primary object of the present invention to provide an improved control system for a satellite delivered Pay-Per-View television system which is more flexible and versatile than previously available systems for switching equipment in the head-end of each cable system of a network of such systems.
Another object of the invention is to provide a system for enabling an individual cable subscriber of any cable system on a network to order from a published schedule a desired PPV program by simply placing a timely telephone call, without voice contact, to the facilities of the program originator.